부산대학교 도서관

The mosquitocidal activities of different fractions and a compound alizarin from the methanol extract of Rubia cordifoliaroots were evaluated on larvae and pupae of Culex quinquefasciatusSay and Aedes aegypti(L.) (Diptera: Culicidae). Larvae and pupae were exposed to concentrations of 2.5, 5.0, 7.5 and 10 ppm for fractions and 0.5, 1.0, 1.5 and 2.0 ppm for compound. After 24 h, the mortality was assessed and the LC50and LC90values were estimated for larvae and pupae. Among the 23 fractions screened, fraction 2 from the methanol extract of R. cordifoliashowed good mosquitocidal activity against C. quinquefasciatusand A. aegypti. LC50and LC90values of fraction 2 were 3.53 and 7.26 ppm for C. quinquefasciatusand 3.86 and 8.28 ppm for A. aegyptilarvae, and 3.76 and 7.50 ppm for C. quinquefasciatusand 3.92 and 8.05 ppm for A. aegyptipupae, respectively. Further, the isolated compound alizarin presented good larvicidal and pupicidal activities. LC50and LC90values of alizarin for larvae were 0.81 and 3.86 ppm against C. quinquefasciatusand 1.31 and 6.04 ppm for A. aegyptilarvae, respectively. Similarly, the LC50and LC90values of alizarin for pupae were 1.97 and 4.79 ppm for C. quinquefasciatusand 2.05 and 5.59 ppm for A. aegyptipupae, respectively. The structure of the isolated compound was identified on the basis of spectroscopic analysis and compared with reported spectral data. The results indicated that alizarin could be used as a potential larvicide and pupicide.